I think you are over thinking this a bit. First if you are using sixteen cells with your battery bank you need one 16S BMS not two 8S BMS (Do not use the 2 - 8S BMS on 16 cells). The numbers you are throwing out there are all maximum scenarios. Like the charger for instance, yes it is rated for 80 amps, but if you are charging with utility, off a home 120v outlet or from a generator, I don't think in this case you can get even near 80 amps off a 20 amp circuit. Charging with solar, you only get to the highest output of the panels between around 10 am and 2 pm. Either side of that time frame the solar panels will be having a lower output.The pic I have attached is my solar production on my home solar from yesterday. 87 kilowatts from 50 - 335 watt solar panels. The pic shows how the solar performs during the day. The whole day was sunny with no clouds. My highest output since Oct. 4th of last year.
My four solar panels for the Growatt put out 8 amps each, so I am not even near the 80 amp limit. With the solar panels, you cannot exceed the total VOC rating of your panels to over 145vdc on the Growatt. On the AC output, I have one 20 amp circuit. I cannot exceed 20 amps on this side of the inverter because of my wire size and breaker.
If your batteries say are in a 50% state of charge, when they start to get charged by the Growatt, they will be charged using bulk mode. This is the highest level charging the batteries get. None of my power sources will put out 80 amps. When the batteries are getting full the Growatt switches to float, then when in a full state of charge the mode is absorption. All of these parameters can be set on the Growatt. I am thinking with my four panels, it will take about 2-1/2 hours to charge my battery on a sunny day during max solar hours 10 am - 2 pm. Longer if I am on either side of that time frame.
The Growatt cannot put out more than 3000 watts. It is rated for that, but in the real world plan on 2600 - 2800 watts. Your big battery set up will get you more storage but it will not increase any output numbers. Your system will be around 4.8 kilowatts of storage. So you could run a 1000 watt load for 4.8 hours. My 2.4 kilowatt battery can run a 1000 watt load for 2.4 hours. These are perfect world scenarios but the actual numbers would be different because we don't want to totally drain the battery. Battery setup which what I was looking for, is to charge the battery to a 85% state of charge on the high end and a 20% state of charge on the low end.